Partial tile rendering

ABSTRACT

In accordance with some embodiments, partial rendering of non-changing or slowly changing frame tiles allows the graphics processing unit to spend less time processing non-changing or slowly changing portions of each frame, saving power and creating more room for performance in some embodiments.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/955,228, filed on Jul. 31, 2013.

BACKGROUND

This relates generally to graphics processing.

The main function of a graphics processing unit is to render frames asrequested by a graphics application. Graphics applications typicallyrender all pixels in a frame buffer regardless of whether the pixelshave changed from frame to frame or not. There are some graphicsapplications, such as casual game applications, that do not tend toupdate large portions of the frame buffer, from frame to frame.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments are described with respect to the following figures:

FIG. 1 is a schematic depiction for one embodiment;

FIG. 2 is a depiction of a partial render cycle according to oneembodiment;

FIG. 3 is a flow chart for one embodiment;

FIG. 4 is a schematic depiction of a system according to one embodiment;and

FIG. 5 is a front elevational view of one embodiment.

DETAILED DESCRIPTION

In accordance with some embodiments, partial rendering of non-changingor slowly changing frame tiles allows the graphics processing unit tospend less time processing non-changing or slowly changing portions ofeach frame, saving power and creating more room for performance.

Thus in some embodiments, frames are broken up into tiles that arerendered separately. The number of tiles in a frame is generally fixedin one embodiment and does not change from frame to frame. However inother embodiments, variable tile sizes and tile counts within a framemay be used. By default, each tile is rendered fully. For example allpixels or 4×4 spans in a tile are rendered normally and updated in theframe buffer. A fully rendered tile is then compared against the sametile in a previous frame to determine whether any pixels may havechanged. If no pixels have changed, then the tile is marked asnon-changing and the partial rendering mode begins. A tile comparisonmay be done using a pixel by pixel comparison across all the pixels oftwo tiles or a sum of absolute differences operation on pixels of twotiles may be used. Other methods of comparing pixels may also be used.The tile comparison may be done in software, such as by a driver, by acompute shader executed on the graphics processing unit or by hardwarefixed function units, in some embodiments. The comparison of two tilesmay determine if the tiles are exactly the same or whether differencesbetween the two tiles are limited to a magnitude under a predeterminedthreshold in which case there is a slow change from one tile to another.A tile may enter partial rendering when it is determined to benon-changing or, in the more general case, slowly changing.

When in the partial rendering mode, a tile is fully rendered and updatedin the frame buffer at a slower rate. This rate may be a submultiple,such as one-third, one-fourth, or one-fifth, of a baseline frame ratethat applies to the whole frame. Thus, in the following discussion, atile “refresh” means that the tile is fully rendered and in fact all itspixels are rendered.

When a non-changing or slowly changing tile is in the partial rendermode, it may be refreshed only once over a number of frames such as 3, 4or 5 frames. This number of frames defines the tile's partial rendercycle. If the tile is refreshed only once every four frames for example,its partial render cycle is four frames long. The refresh rate ofdifferent non-changing tiles need not be the same, in the general case.Also, the start of the partial render cycle of a tile need not coincidewith that of another tile.

A non-changing tile is refreshed on the first frame of its partialrender cycle in one embodiment. The rest of the time the tile is“partially rendered,” meaning only a portion of the pixels or spans inthe tile is computed normally for the purpose of enabling a comparisonof those pixels with the same pixels of the tile in a previous frame.The previous frame may be the last time that the tile was fullyrendered. If this comparison shows that the tile has likely not changedsince the previous frame, the rest of its pixels are not rendered andinstead they are copied from the previous frame.

Partial rendering may be done using an appropriate stencil buffer ordepth buffer that skips pixel shading of pixels that are not to berendered by a stencil mask or early depth cull.

Vertex shading is still done for the entire geometry in the whole framebut pixel shading may be localized and may occur for the targeted tilepixels at a reduced rate due to the early depth culling or stencilrejection. Vertex shading typically accounts for a smaller portion ofthe total graphics processing compute effort so saving pixel shadinggraphics processor cycles may have a larger impact on graphics powerconsumption. Reducing pixel shading work generally reduces graphicprocessing unit power dissipation more than input/output powerdissipation consumed to copy non-changing frame tiles from the previousframe into the current frame.

The pixels that are rendered may be spread throughout the tile areaeither randomly or based on a pattern, such as every fourth or fifthpixel or span of the tile. Spreading out the rendered pixels mayincrease the probability that if some change occurs within the time fromframe to frame, that change will be detected in the subset of pixelsthat were rendered, since a change in one pixel usually affects a numberof neighboring pixels.

A partially rendered tile may have the same subset of pixels rendered ina pair of back to back frames so that those pixels can be compared.However, a different subset of pixels may be rendered in a subsequentpair of frames so that the comparison may cover more tile pixels overtime. When a tile is in the partial render mode there is a tensionbetween rendering more tile pixels, to increase the probability that achange is detected, and rendering fewer pixels, so that power savingscan be increased.

Referring to FIG. 1, in accordance with one embodiment, a graphicsprocessing unit 10 includes a tiler 12 that divides a frame into tilesof a desired size. The smaller the tile size that is selected, the morelikely it is that tiles that are unchanging will be identified. Thetiler 12 receives a tile size input from the tile size unit 14. In oneembodiment the tile size may come from a graphics application.

The tiler provides the tiles to a tile change detector 16 which may useany of the techniques described previously or other techniques thatdetermine whether successive tiles have pixels whose values arechanging. A frame counter 18 may provide the tile change detector withan indication of how many frames have passed since a particular tilechanged or since the last time a non-changing tile was refreshed. Theframe counter may also keep track of the individual partial render cycleof each non-changing tile.

Finally rendering occurs on a tile by tile basis at renderer 20 in oneembodiment.

Referring to FIG. 2, an example involving a series of frames with anon-changing tile in the upper left corner of each frame is shown. Thenon-changing tile is refreshed every four frames in this example, so thepartial render cycle is four frames long. A tile is rendered partiallyand copied over from the previous frame in the second, third, fourthframes of each partial render cycle. The tile refresh rate and thepartial render cycle length need not remain fixed, but rather may varyover time. If a pixel change is detected within a partially renderedtile, the tile exits the partial render mode immediately and is fullyrendered starting with the following frame in one embodiment.

There is a possibility that a change that occurs in a partially renderedtile may go undetected initially, if it has occurred in pixels orsubspans that were not rendered and were not immediately compared. Thismay cause the tile to continue to be refreshed at a lower rate for alonger time until the change does get detected. Hence the comparisons ofpartially rendered tiles to previous versions of the same tile may bedone in an efficient manner so that changes that may have occurred aredetected as soon as possible and so that the tile can exit partialrender mode and start getting rendered at the full frame rate again.

Many techniques may be used for detecting changes in non-changing tileswith varying degrees of complexity and efficiency. For example, thesubset of rendered tile pixels may be the same in a pair of frames so asto insure that the pixel comparisons can be done in a meaningful way.One simple tile comparison technique compares the exact same subset oftile pixels between neighboring frames for the entire duration of thepartial render cycle. One variation of this scheme is that, in thesubsequent pair of frames, a different subset of tile pixels arerendered and compared than in the previous pair of frames, so that overtime more tile pixels are rendered and compared. For example, referringto FIG. 2, the upper left tile may be compared between the first andsecond frames using a certain subset of its pixels, and then comparedbetween the third and fourth frames using a different subset of itspixels. According to still another technique, which may be used inaddition to or as an alternative to the techniques described above, eachnon-changing tile may be compared fully at the start of each new partialrender cycle with the same tile at the start of the previous partialrender cycle. A nonchanging tile may be rendered fully at the start ofeach partial render cycle. This full rendering enables a full pixel bypixel comparison of the tile with the previous version of the same tilea few frames back and guarantees that any change that occurred in thetile since the start of the last render cycle is detected. So if thepartial render cycle is four frames long, then any change that occurredin the tile during the last four frames is detected at the start of thenext partial render cycle at the very latest. The change could bedetected earlier as well, depending on which subset of tile pixels wasrendered and compared during the partial render cycle. Essentially, apartial render cycle of four frames insures that a non-changing tile isrefreshed at a rate that is at least one-fourth of the baseline framerate. Rendering partially this and other non-changing tiles likely savesenough power to raise the graphics processing unit frequency andbaseline frame rate, so the refresh rate of the non-changing tile may beguaranteed to be at least one-fourth of an increased baseline frame ratein some embodiments.

These detection schemes may involve storing in memory a few of thepreviously rendered frames, since each non-changing tile in a frame mayhave its own individual partial render cycle length, typically two tofive frames long. So at any time any non-changing tile may involve acomparison to pixels in a frame up to five frames back.

Different policies may be used to determine the rate of tile refresh.One policy is that the faster the baseline frame rate, the lower therelative refresh rate of an unchanging tile. At the same time, it may beassured that a minimum tile refresh rate is preserved, such as 10 framesper second. Thus, as an example if the frame base rate is 60 frames persecond, a non-changing tile may be refreshed at 60 frames per seconddivided by 5 or 12 frames per second. If the baseline frame rate dropsto 49 frames per second, then a non-changing tile may be refreshed at 49frames per second divided by 4 equals 12.3 frames per second and so on.

Referring to FIG. 3, a sequence for partial tile rendering according toone embodiment may be implemented in software, firmware and/or hardware.In software and firmware embodiments it may be implemented by computerexecuted instructions stored in one or more non-transitory computerreadable media such as a magnetic, optical or semiconductor storage.

The sequence shown in FIG. 3 includes a loop that repeats sequentiallyfor every tile in the frame. In another embodiment, each tile can beprocessed in parallel. A changing tile is fully rendered. It is alsofully compared against the same tile in the previous frame to detect achange in this embodiment. A non-changing tile is rendered fully only atthe start of its partial render cycle according to one embodiment. Therest of the time the non-changing tile is rendered partially and it iscompared against the previous frame. If the tile continues to benon-changing, it is copied into the frame buffer from the previous framebecause the tile does not need to be fully rendered. However if a changeis detected in the tile that is currently considered to be non-changing,then the tile is marked as changing so that it can be fully rendered onthe following frame.

The first time a tile is flagged as non-changing, it is at the start ofa partial render cycle. At that point, a counter (for example seecounter 18 in FIG. 1) is updated for the tile to determine the length ofits partial render cycle. For example if the partial render cycle isfour frames long, the counter is set to 4−1=3. In every one of thefollowing frames where the tile remains unchanged, the tile continues tobe flagged as non-changing and its partial render cycle counterdecrements. When the counter gets to zero, the tile is fully rendered,regardless of whether it continues to be unchanging or not.

Thus, referring to FIG. 3, all tiles are marked as “changing” and Nequals the number of tiles in a frame, as indicated in block 30. Thenext frame is then selected and i is set equal to 1 in block 32. A checkat diamond 34 determines whether i is less than or equal to the numberof frames N. If not, the flow goes back to get another frame at block32. If so, the flow goes to block 36. If the tile is changing, or ifthere is a non-changing tile and it is at the start of a partial rendercycle, then all the pixels in the tile are rendered and compared againstthe previous frame. Otherwise a subset of the tile pixels are renderedand compared against a previous frame. The rest of the pixels are copiedfrom the previous frame and the file is updated in the frame buffer. Atthis point there are no updates in the frame buffer.

At block 38 a check determines whether the tile has changed. If not, thetile is marked as non-changing in block 42. A check at diamond 44determines if this is a start of a partial render cycle. If not, thetile partial render cycle counter is decremented in block 48.

If this is a start of a render cycle, as determined in diamond 44, thenthe tile refresh rate is determined as indicated in block 46 and thepartial render cycle counter is set. The variable i is incremented by 1as indicated in block 50 and the flow iterates.

If the tile has changed as determined in diamond 38, then the tile ismarked as changing in block 40.

The quality of the frame stream rendered is dependent on the length ofthe partial render cycle for each non-changing tile. If the partialrendering cycle length is reasonably small, for example 3 or 4 frames,then in the event that the tile contained a change that went undetected,the tile is still fully rendered no more than three or four frameslater, so that a minimum refresh rate for the tile is guaranteed. Thismay help in reducing visual artifacts.

Most of the partial render algorithm described herein may be implementedvia compute shaders running on a graphics processing unit. However,partial tile render performance may be improved with special purposefixed function hardware designed to quickly and efficiently compareframe tiles in the RGB format.

In some embodiments power dissipation may be reduced and performance maybe increased, when rendering graphics frames that include portions thatremain unchanged over a period of time. Thus by combining concepts oftiling and lack of change detection, in order to reduce the refresh rateof individual tiles in the frame, power savings may be achieved byemploying partial rendering of non-changing tiles.

The same techniques may also be extended to reduce a refresh rate ofslowly changing tiles such as tiles that contain a small amount ofchange as measured by a predefined measure. For example, one measure ofchange may be a sum of absolute difference threshold value from frame toframe. Then more slowly changing tiles (below the threshold) may takeadvantage of the fact that they include a smaller degree of change andmay be fully rendered at a slower rate relative to the baseline framerate, since it is typically the fast changing geometries that benefitmost from the higher render rate.

FIG. 4 illustrates an embodiment of a system 700. In embodiments, system700 may be a media system although system 700 is not limited to thiscontext. For example, system 700 may be incorporated into a personalcomputer (PC), laptop computer, ultra-laptop computer, tablet, touchpad, portable computer, handheld computer, palmtop computer, personaldigital assistant (PDA), cellular telephone, combination cellulartelephone/PDA, television, smart device (e.g., smart phone, smart tabletor smart television), mobile internet device (MID), messaging device,data communication device, and so forth.

In embodiments, system 700 comprises a platform 702 coupled to a display720. Platform 702 may receive content from a content device such ascontent services device(s) 730 or content delivery device(s) 740 orother similar content sources. A navigation controller 750 comprisingone or more navigation features may be used to interact with, forexample, platform 702 and/or display 720. Each of these components isdescribed in more detail below.

In embodiments, platform 702 may comprise any combination of a chipset705, processor 710, memory 712, storage 714, graphics subsystem 715,applications 716 and/or radio 718. Chipset 705 may provideintercommunication among processor 710, memory 712, storage 714,graphics subsystem 715, applications 716 and/or radio 718. For example,chipset 705 may include a storage adapter (not depicted) capable ofproviding intercommunication with storage 714.

Processor 710 may be implemented as Complex Instruction Set Computer(CISC) or Reduced Instruction Set Computer (RISC) processors, x86instruction set compatible processors, multi-core, or any othermicroprocessor or central processing unit (CPU). In embodiments,processor 710 may comprise dual-core processor(s), dual-core mobileprocessor(s), and so forth. The processor may implement the sequence ofFIG. 3 together with memory 712.

Memory 712 may be implemented as a volatile memory device such as, butnot limited to, a Random Access Memory (RAM), Dynamic Random AccessMemory (DRAM), or Static RAM (SRAM).

Storage 714 may be implemented as a non-volatile storage device such as,but not limited to, a magnetic disk drive, optical disk drive, tapedrive, an internal storage device, an attached storage device, flashmemory, battery backed-up SDRAM (synchronous DRAM), and/or a networkaccessible storage device. In embodiments, storage 714 may comprisetechnology to increase the storage performance enhanced protection forvaluable digital media when multiple hard drives are included, forexample.

Graphics subsystem 715 may perform processing of images such as still orvideo for display. Graphics subsystem 715 may be a graphics processingunit (GPU) or a visual processing unit (VPU), for example. An analog ordigital interface may be used to communicatively couple graphicssubsystem 715 and display 720. For example, the interface may be any ofa High-Definition Multimedia Interface, DisplayPort, wireless HDMI,and/or wireless HD compliant techniques. Graphics subsystem 715 could beintegrated into processor 710 or chipset 705. Graphics subsystem 715could be a stand-alone card communicatively coupled to chipset 705.

The graphics and/or video processing techniques described herein may beimplemented in various hardware architectures. For example, graphicsand/or video functionality may be integrated within a chipset.Alternatively, a discrete graphics and/or video processor may be used.As still another embodiment, the graphics and/or video functions may beimplemented by a general purpose processor, including a multi-coreprocessor. In a further embodiment, the functions may be implemented ina consumer electronics device.

Radio 718 may include one or more radios capable of transmitting andreceiving signals using various suitable wireless communicationstechniques. Such techniques may involve communications across one ormore wireless networks. Exemplary wireless networks include (but are notlimited to) wireless local area networks (WLANs), wireless personal areanetworks (WPANs), wireless metropolitan area network (WMANs), cellularnetworks, and satellite networks. In communicating across such networks,radio 718 may operate in accordance with one or more applicablestandards in any version.

In embodiments, display 720 may comprise any television type monitor ordisplay. Display 720 may comprise, for example, a computer displayscreen, touch screen display, video monitor, television-like device,and/or a television. Display 720 may be digital and/or analog. Inembodiments, display 720 may be a holographic display. Also, display 720may be a transparent surface that may receive a visual projection. Suchprojections may convey various forms of information, images, and/orobjects. For example, such projections may be a visual overlay for amobile augmented reality (MAR) application. Under the control of one ormore software applications 716, platform 702 may display user interface722 on display 720.

In embodiments, content services device(s) 730 may be hosted by anynational, international and/or independent service and thus accessibleto platform 702 via the Internet, for example. Content servicesdevice(s) 730 may be coupled to platform 702 and/or to display 720.Platform 702 and/or content services device(s) 730 may be coupled to anetwork 760 to communicate (e.g., send and/or receive) media informationto and from network 760. Content delivery device(s) 740 also may becoupled to platform 702 and/or to display 720.

In embodiments, content services device(s) 730 may comprise a cabletelevision box, personal computer, network, telephone, Internet enableddevices or appliance capable of delivering digital information and/orcontent, and any other similar device capable of unidirectionally orbidirectionally communicating content between content providers andplatform 702 and/display 720, via network 760 or directly. It will beappreciated that the content may be communicated unidirectionally and/orbidirectionally to and from any one of the components in system 700 anda content provider via network 760. Examples of content may include anymedia information including, for example, video, music, medical andgaming information, and so forth.

Content services device(s) 730 receives content such as cable televisionprogramming including media information, digital information, and/orother content. Examples of content providers may include any cable orsatellite television or radio or Internet content providers. Theprovided examples are not meant to limit embodiments of the invention.

In embodiments, platform 702 may receive control signals from navigationcontroller 750 having one or more navigation features. The navigationfeatures of controller 750 may be used to interact with user interface722, for example. In embodiments, navigation controller 750 may be apointing device that may be a computer hardware component (specificallyhuman interface device) that allows a user to input spatial (e.g.,continuous and multi-dimensional) data into a computer. Many systemssuch as graphical user interfaces (GUI), and televisions and monitorsallow the user to control and provide data to the computer or televisionusing physical gestures.

Movements of the navigation features of controller 750 may be echoed ona display (e.g., display 720) by movements of a pointer, cursor, focusring, or other visual indicators displayed on the display. For example,under the control of software applications 716, the navigation featureslocated on navigation controller 750 may be mapped to virtual navigationfeatures displayed on user interface 722, for example. In embodiments,controller 750 may not be a separate component but integrated intoplatform 702 and/or display 720. Embodiments, however, are not limitedto the elements or in the context shown or described herein.

In embodiments, drivers (not shown) may comprise technology to enableusers to instantly turn on and off platform 702 like a television withthe touch of a button after initial boot-up, when enabled, for example.Program logic may allow platform 702 to stream content to media adaptorsor other content services device(s) 730 or content delivery device(s)740 when the platform is turned “off.” In addition, chip set 705 maycomprise hardware and/or software support for 5.1 surround sound audioand/or high definition 7.1 surround sound audio, for example. Driversmay include a graphics driver for integrated graphics platforms. Inembodiments, the graphics driver may comprise a peripheral componentinterconnect (PCI) Express graphics card.

In various embodiments, any one or more of the components shown insystem 700 may be integrated. For example, platform 702 and contentservices device(s) 730 may be integrated, or platform 702 and contentdelivery device(s) 740 may be integrated, or platform 702, contentservices device(s) 730, and content delivery device(s) 740 may beintegrated, for example. In various embodiments, platform 702 anddisplay 720 may be an integrated unit. Display 720 and content servicedevice(s) 730 may be integrated, or display 720 and content deliverydevice(s) 740 may be integrated, for example. These examples are notmeant to limit the invention.

In various embodiments, system 700 may be implemented as a wirelesssystem, a wired system, or a combination of both. When implemented as awireless system, system 700 may include components and interfacessuitable for communicating over a wireless shared media, such as one ormore antennas, transmitters, receivers, transceivers, amplifiers,filters, control logic, and so forth. An example of wireless sharedmedia may include portions of a wireless spectrum, such as the RFspectrum and so forth. When implemented as a wired system, system 700may include components and interfaces suitable for communicating overwired communications media, such as input/output (I/O) adapters,physical connectors to connect the I/O adapter with a correspondingwired communications medium, a network interface card (NIC), disccontroller, video controller, audio controller, and so forth. Examplesof wired communications media may include a wire, cable, metal leads,printed circuit board (PCB), backplane, switch fabric, semiconductormaterial, twisted-pair wire, co-axial cable, fiber optics, and so forth.

Platform 702 may establish one or more logical or physical channels tocommunicate information. The information may include media informationand control information. Media information may refer to any datarepresenting content meant for a user. Examples of content may include,for example, data from a voice conversation, videoconference, streamingvideo, electronic mail (“email”) message, voice mail message,alphanumeric symbols, graphics, image, video, text and so forth. Datafrom a voice conversation may be, for example, speech information,silence periods, background noise, comfort noise, tones and so forth.Control information may refer to any data representing commands,instructions or control words meant for an automated system. Forexample, control information may be used to route media informationthrough a system, or instruct a node to process the media information ina predetermined manner. The embodiments, however, are not limited to theelements or in the context shown or described in FIG. 4.

As described above, system 700 may be embodied in varying physicalstyles or form factors. FIG. 5 illustrates embodiments of a small formfactor device 800 in which system 700 may be embodied. In embodiments,for example, device 800 may be implemented as a mobile computing devicehaving wireless capabilities. A mobile computing device may refer to anydevice having a processing system and a mobile power source or supply,such as one or more batteries, for example.

As described above, examples of a mobile computing device may include apersonal computer (PC), laptop computer, ultra-laptop computer, tablet,touch pad, portable computer, handheld computer, palmtop computer,personal digital assistant (PDA), cellular telephone, combinationcellular telephone/PDA, television, smart device (e.g., smart phone,smart tablet or smart television), mobile internet device (MID),messaging device, data communication device, and so forth.

Examples of a mobile computing device also may include computers thatare arranged to be worn by a person, such as a wrist computer, fingercomputer, ring computer, eyeglass computer, belt-clip computer, arm-bandcomputer, shoe computers, clothing computers, and other wearablecomputers. In embodiments, for example, a mobile computing device may beimplemented as a smart phone capable of executing computer applications,as well as voice communications and/or data communications. Althoughsome embodiments may be described with a mobile computing deviceimplemented as a smart phone by way of example, it may be appreciatedthat other embodiments may be implemented using other wireless mobilecomputing devices as well. The embodiments are not limited in thiscontext.

The processor 710 may communicate with a camera 722 and a globalpositioning system sensor 720, in some embodiments. A memory 712,coupled to the processor 710, may store computer readable instructionsfor implementing the sequences shown in FIG. 3 in software and/orfirmware embodiments.

As shown in FIG. 5, device 800 may comprise a housing 802, a display804, an input/output (I/O) device 806, and an antenna 808. Device 800also may comprise navigation features 812. Display 804 may comprise anysuitable display unit for displaying information appropriate for amobile computing device. I/O device 806 may comprise any suitable I/Odevice for entering information into a mobile computing device. Examplesfor I/O device 806 may include an alphanumeric keyboard, a numerickeypad, a touch pad, input keys, buttons, switches, rocker switches,microphones, speakers, voice recognition device and software, and soforth. Information also may be entered into device 800 by way ofmicrophone. Such information may be digitized by a voice recognitiondevice. The embodiments are not limited in this context.

Various embodiments may be implemented using hardware elements, softwareelements, or a combination of both. Examples of hardware elements mayinclude processors, microprocessors, circuits, circuit elements (e.g.,transistors, resistors, capacitors, inductors, and so forth), integratedcircuits, application specific integrated circuits (ASIC), programmablelogic devices (PLD), digital signal processors (DSP), field programmablegate array (FPGA), logic gates, registers, semiconductor device, chips,microchips, chip sets, and so forth. Examples of software may includesoftware components, programs, applications, computer programs,application programs, system programs, machine programs, operatingsystem software, middleware, firmware, software modules, routines,subroutines, functions, methods, procedures, software interfaces,application program interfaces (API), instruction sets, computing code,computer code, code segments, computer code segments, words, values,symbols, or any combination thereof. Determining whether an embodimentis implemented using hardware elements and/or software elements may varyin accordance with any number of factors, such as desired computationalrate, power levels, heat tolerances, processing cycle budget, input datarates, output data rates, memory resources, data bus speeds and otherdesign or performance constraints.

The following clauses and/or examples pertain to further embodiments:

One example embodiment may be a method comprising splitting a frame intotiles, determining whether pixels in a tile change from one frame toanother frame by an amount, fully rendering the tile if the pixel changeis detected; and partially rendering the tile if the pixel change is notdetected. The method may also include detecting a pixel change of anyextent. The method may also include detecting tiles with pixels thatchange by an amount above a threshold. The method may also includewherein partially rendering includes fully rendering the tile after agiven number of frames. The method may also include determining againwhether pixels in the tile that did not change by an amount, changeafter a given number of frames. The method may also include comparingthe tile after the given number of frames to the same tile in theimmediately preceding frame. The method may also include comparing thetile after the given number of frames to the pixels in the tile at thebeginning of the given number of frames. The method may also includedetermining including comparing the same pixels in a pair of successivetiles. The method may also include comparing a first set of pixels intwo successive tiles and a different set of pixels in two subsequenttiles.

Another example embodiment may be one or more non-transitory computerreadable media storing instructions to enable a processor to perform asequence comprising splitting a frame into tiles, determining whetherpixels in a tile change from one frame to another frame by an amount,fully rendering the tile if the pixel change is detected, and partiallyrendering the tile if the pixel change is not detected. The media mayfurther store said sequence including detecting a pixel change of anyextent. The media may further store said sequence including detectingtiles with pixels that change by an amount above a threshold. The mediamay further store said sequence wherein partially rendering includesfully rendering the tile after a given number of frames. The media mayfurther store said sequence including determining again whether pixelsin the tile that did not change by an amount, change after a givennumber of frames. The media may further store said sequence includingcomparing the tile after the given number of frames to the same tile inthe immediately preceding frame. The media may further store saidsequence including comparing the tile after the given number of framesto the pixels in the tile at the beginning of the given number offrames. The media may further store wherein determining includingcomparing the same pixels in a pair of successive tiles. The media mayfurther store said sequence including comparing a first set of pixels intwo successive tiles and a different set of pixels in two subsequenttiles.

In another example embodiment may be a graphics processing unitcomprising a processor to split a frame into tiles, determine whetherpixels in a tile change from one frame to another frame by an amount,fully render the tile if the pixel change is detected, and partiallyrender the tile if the pixel change is not detected, and a storagecoupled to said processor. The unit may include said processor to detecta pixel change of any extent. The unit may include said processor todetect tiles with pixels that change by an amount above a threshold. Theunit may include said processor to partially render by fully renderingthe tile after a given number of frames. The unit may include saidprocessor to determine again whether pixels in the tile that did notchange by an amount, change after a given number of frames. The unit mayinclude said processor to compare the tile after the given number offrames to the same tile in the immediately preceding frame. The unit mayinclude said processor to compare the tile after the given number offrames to the pixels in the tile at the beginning of the given number offrames. The unit may include said processor to determine by comparingthe same pixels in a pair of successive tiles. The unit may include saidprocessor to compare a first set of pixels in two successive tiles and adifferent set of pixels in two subsequent tiles. The unit may include anoperating system, a battery and firmware and a module to update saidfirmware.

The graphics processing techniques described herein may be implementedin various hardware architectures. For example, graphics functionalitymay be integrated within a chipset. Alternatively, a discrete graphicsprocessor may be used. As still another embodiment, the graphicsfunctions may be implemented by a general purpose processor, including amulticore processor.

References throughout this specification to “one embodiment” or “anembodiment” mean that a particular feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneimplementation encompassed within the present disclosure. Thus,appearances of the phrase “one embodiment” or “in an embodiment” are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics may be instituted inother suitable forms other than the particular embodiment illustratedand all such forms may be encompassed within the claims of the presentapplication.

While a limited number of embodiments have been described, those skilledin the art will appreciate numerous modifications and variationstherefrom. It is intended that the appended claims cover all suchmodifications and variations as fall within the true spirit and scope ofthis disclosure.

What is claimed is:
 1. A method comprising: splitting a frame intotiles; partially rendering a tile in a current frame including aplurality of pixels by rendering, less than all of said pixels;comparing the rendered pixels in the current frame with correspondingpixels from a tile in a previous frame; if any partially rendered pixelin the current frame is different from the corresponding pixel in theprevious frame by an amount exceeding a threshold, completely renderingthe tile in a fully rendering mode; if no partially rendered pixel isdifferent from the corresponding pixel in the previous frame by anamount exceeding the threshold, then copying the previous frame insteadof completing the rendering of the current frame; and when in a partialrendering mode, a tile is fully rendered and updated in a frame bufferat a slower rate than when in a fully rendering mode.
 2. The method ofclaim 1 including detecting a pixel change of any extent.
 3. The methodof claim 1 including detecting tiles with pixels that change by anamount above a threshold.
 4. The method of claim 1 wherein partiallyrendering includes fully rendering the tile after a given number offrames.
 5. The method of claim 4 including determining again whetherpixels in the tile that did not change by an amount, change after agiven number of frames.
 6. The method of claim 4 including comparing thetile after the given number of frames to the same tile in theimmediately preceding frame.
 7. The method of claim 4 includingcomparing the tile after the given number of frames to the pixels in thetile at the beginning of the given number of frames.
 8. The method ofclaim 1 wherein determining including comparing the same pixels in apair of successive tiles.
 9. The method of claim 1 including comparing afirst set of pixels in two successive tiles and a different set ofpixels in two subsequent tiles.
 10. One or more non-transitory computerreadable media storing instructions to enable a processor to perform asequence comprising: splitting a frame into tiles; partially rendering atile in a current frame including a plurality of pixels by rendering,less than all of said pixels; comparing the rendered pixels in thecurrent frame with corresponding pixels from a tile in a previous frame;if any partially rendered pixel in the current frame is different fromthe corresponding pixel in the previous frame by an amount exceeding athreshold, completely rendering the tile in a fully rendering mode; ifno partially rendered pixel is different from the corresponding pixel inthe previous frame by an amount exceeding the threshold, then copyingthe previous frame instead of completing the rendering of the currentframe; and when in a partial rendering mode, a tile is fully renderedand updated in a frame buffer at a slower rate than when in a fullyrendering mode.
 11. The media of claim 10 said sequence includingdetecting a pixel change of any extent.
 12. The media of claim 10 saidsequence including detecting tiles with pixels that change by an amountabove a threshold.
 13. The media of claim 10 said sequence whereinpartially rendering includes fully rendering the tile after a givennumber of frames.
 14. The media of claim 13 said sequence includingdetermining again whether pixels in the tile that did not change by anamount, change after a given number of frames.
 15. The media of claim 13said sequence including comparing the tile after the given number offrames to the same tile in the immediately preceding frame.
 16. Themedia of claim 13 said sequence including comparing the tile after thegiven number of frames to the pixels in the tile at the beginning of thegiven number of frames.
 17. The media of claim 10 wherein determiningincluding comparing the same pixels in a pair of successive tiles. 18.The media of claim 10 said sequence including comparing a first set ofpixels in two successive tiles and a different set of pixels in twosubsequent tiles.
 19. A graphics processing unit comprising: a processorto split a frame into tiles, to partially render a tile in a currentframe including a plurality of pixels by rendering, less than all ofsaid pixels, compare the rendered pixels in the current frame withcorresponding pixels from a tile in a previous frame, if any partiallyrendered pixel in the current frame is different from the correspondingpixel in the previous frame by an amount exceeding a threshold,completely render the tile in a fully rendering mode, if no partiallyrendered pixel is different from the corresponding pixel in the previousframe by an amount exceeding the threshold, then copy the previous frameinstead of completing the rendering of the current frame, when in apartial rendering mode, a tile is fully rendered and updated in a framebuffer at a slower rate than when in a fully rendering mode; and astorage coupled to said processor.
 20. The unit of claim 19 saidprocessor to detect a pixel change of any extent.
 21. The unit of claim19 said processor to detect tiles with pixels that change by an amountabove a threshold.
 22. The unit of claim 19 said processor to partiallyrender by fully rendering the tile after a given number of frames. 23.The unit of claim 22 said processor to determine again whether pixels inthe tile that did not change by an amount, change after a given numberof frames.
 24. The unit of claim 22 said processor to compare the tileafter the given number of frames to the same tile in the immediatelypreceding frame.
 25. The unit of claim 19 said processor to compare thetile after the given number of frames to the pixels in the tile at thebeginning of the given number of frames.
 26. The unit of claim 19, saidprocessor to determine by comparing the same pixels in a pair ofsuccessive tiles.
 27. The unit of claim 19 said processor to compare afirst set of pixels in two successive tiles and a different set ofpixels in two subsequent tiles.
 28. The unit of claim 19 including anoperating system.
 29. The unit of claim 19 including a battery.
 30. Theunit of claim 19 including firmware and a module to update saidfirmware.